Signaling system



Ami! 16, 1946.

M. w. MUEH TER SIGNALING SYSTEM 2 Sheets-Sheet 1 Origipal Filed Aug. 3, 1940 INVENTOR M. W. MU EHTER ATTORNEY April 16, 1946.

M. W. MUEHTER SIGNALING SYSTEM Original Filed Aug. 3/1940 2 Sheets-Sheet 2 Kuhn-0mm INVENTOR M. W. MUEHTER BY 11 v w wE ATTORNEY Patented Apr. 16, 1946 SIGNALING SYSTEM Manfred W. Muehter, Nutley, N. J., assignor to Q American District Telegraph Company, Jersey City, N. J a corporation of New Jersey Original application August '3, 1940, Serial No.

350,623. Divided and this application December 16, 1944, Serial No. 568,519

This invention relates generally to Signaling systems and more particularly to such systems used for transmission and reception of fire alarm, waterflow alarm, watchmans tour and burglar signals. V This application is a division of my copending application .Serial No. 350,623, filed August 3, 1940, for Signaling system, Patent No. 2,365,719, issued December 26, 1944. 3

The system is particularly adapted for automatically receiving signals of the types outlined above, making a record ofthe signals and retransmitting certain ofthe signals, such as fire and police alarm signals to the fire or police headquarters. Prior systems have required manual, retransmission and also manual attention during troubleconditions. This system provides automatic line switching andclearing apparatus for controlling and enabling the system to receive signals even though the various types of line fault conditions occur. Furthermore, the equipment functions without adjustment with any amount of leakage on the line circuit provided it is'only on one side of a transmitter in. operation. Prior McCulloh systems, both manual and automatic, have required relay adjustments, particularly during leakage conditions, these adjustments necessarily distorting the signals and frequently changing to cause loss of signals. I This system also incorporates a different type of signal which comprises break impulses and simultaneous make and ground impulses, thereby eliminating the prior normal impulse which is necessary in McCulloh systems of the old types. Elimination of the normal impulses permits more of the line time or th digit time to be devoted to the other forms of impulses whereby all impulses may be of longe duration. The transmitters used in the system are equipped with commutator type code Wheels instead of the usual pen Spring type, thereby eliminating the necessity of any adjustment in the field and also maintaining a constant impulse ratio. it

The primary object of the invention is to provide a new and improved central station signal receiving and retransmitting apparatus.

Another object of the invention is to provide Further objects and advantages of this invention will be apparent to those skilled in the art through the line and ground relays Land G, re-

after consideration ofth following specification taken in connectionjw'ith the accompanying drawings, wherein; I Fig. 1 is a circuitdiagram illustrating a signal transmission circuit together with the signal receiving relays;

Fig. 2 is a circuit diagram-pf the timing and routing relay together-with a register; and

Fig. 3 illustrates the, preferred form .of transmitter code Wheel which is usedin the transmitters on the line circuit.

The invention will now be described generally in order, to convey axgeneraldmpression of the circuit layout. The systemjis' providedwith transmission line I in the form er; a, map including any desired number of transmitters 2.

Each transmitter is equippediwith a commutator type code wheel having successive conducting segments therein, as illustrated-in Fig. 3101; the drawings.

one side of the transmitter loop. The two code Wheels are electrically connected together on the same shaft and in addition a ground wheel is also mounted on the same shaft for the purpose of grounding thetransmitter wheel during their operation. Theground wheel is provided with an undercut ;;portion which normally. or in the rest position removes ground from the code wheels. Referring to] Fig. 3, code wheel normally rests in the position shown and rotates in the direction indicated by the arrow. The esment 62 ineach of the cod wheels, together with the contact spring 6|, maintain the line circuit in a normally closed condition whereby a supervisory circuit is provided. When the code wheel 60 is rotated, the line is broken by the long space following segment 62, this space being followed by a prefix digit consisting of three make and ground impulses, as 'illustrated in Fig. 3 by way of example only. Each type of alarm is assigned a particular code prefix' digit'whereby the signal may be identified at. the central station. The prefix digit is followed by a space somewhat shorter than the initialbreaksignal space where- .by the central station apparatus may identify the;first digit of the number code which follows the prefix digit. As thewheel 60 continues its rotation, the number digits are t ansmitted until the long break; impulse at the end of the signal terminates the operation of the central station apparatus and restores the line circuittonormal when pring Slcontacts the segment 62;

Signals are ,received at the central oflice There are two suchfcodewheels in each transmitter, eachwheel being connected to spectively. The line and ground relays in turn control a repeating relay R. However, if trouble conditions occur in the line circuit l, the B relay operates in the event of breaks in the line and makes appropriate switching operations for continuing relays L and G in operation to control the relay R. If the trouble conditions are in the nature of grounds either in the lines or in the boxes, the Q relay switche the winding of the relay R to render them operative under the control of the relays L and G.

In Fig. 2 of the drawings, the relay T is a digit timing relay which ascertains the end of each digit and the end of each prefix, while the relay TT is a main timing relay for timing the duration of one round of signals and restoring theapparatus to normal for receiving a succeeding round of signals.

The relays X, Y and Z perform a routing function. and respond-to various prefix digits for routing special signals, such as fire and police alarm signals to the fire and police headquarters trans mitting relays F. HQ. and P. I-LQ.

.Relays U and V are auxiliary switchin .relays for controlling the timing of relay TT and performing other special switching, functions which will be described in greater detail in the follow- 'LINE' SUPERVISING CIRCUIT The normally supervisedline circuit may be traced from plus battery through relay winding GI, out'through the line circuit I. After passing through the transmitters 2 of the line circuit, the

circuit is completed through back contracts 4 of relay Q, and 3 of relay B, through windingLl, through back contacts '8 of relay B and l of relay Q, winding G2 and contact. I'O oi'relay B to ground.

The linerelay L is normally energized and relay I G unoperated owing to the fact that the windings GI and G2 are differentially wound.

NORMAL CONDITIONS .OPERATION or A TRANSMITTER Transmitters used with this system are equipped with commutator type code wheels instead of the usual type employing'penjs'prings. In the normal restpositionofthe transmitter the line circuits are closed between the two line brushes through the normal segments and hub on the commutator. In the 'normal position, the ground is removed from the commutator by means of an undercut portion on the hub segment. After the normal segment, it will be noted that there is abreak equivalent to approximately three tooth spaces, which is to allow suflicient time for switching operations, to be described at a later point. After this break impulse the'code may be cut as required.

NORMAL LINE-CIRCUIT OPERATION First break impulse Assuming a transmitter to be in operation, at the time of the first break impulse when the code wheel springs leave the normal segment, relay L is deenergized due to the opening in the line circuit through its winding Ll. 'With release of relay L, relay B is energized through circuits traced from ground'through back contacts 2 or relay L, [2 of relay B, 8 of relay Q, and winding BR to plus battery. Relay Blocks in'through the circuit traced through back contact8of relayQ, make cOntac't-S of relay Bto ground,'later impulses of a digit of the code.

also through conductor 20 and multiple contacts 5 of relay TT and 5 of relay T and make contact H of relay B. Relay R is energized through the circuit traced from ground through back contact 2 of relay L, through winding R2, back contacts 15 of relay Qand I of relay Gto plus.

'5 of relay B, ll] of relay R, and I6 of relay T, winding TT to ground. Relay TT locks in through the circuit traced from plus, through make contact 8 of relay TT, winding TT and to ground. Shortly after the operation of relay R, relay T drops "out due to ".the shunt across its windings by make contact 50f relay R and line.

At this time it will be mentioned that relays T and TT are slow to release relays, the delayed release being obtained by means of a shunt across each of their respective windings. This delay, in the case of relay T, issuflicient to prevent its falling out on the break between ground The delay on relay TT is sufficient to prevent dropping out between digits of a code. With the release of relay T, relay X is energized through the circuit traced'from plus-throughmake contact I of relay R, line 2 back contacts ioi relay Y, 1 of relay Z, 9 of relay T, and winding XI to minus.

Line circuit switching the line I is switched by the B relay contacts through make contact 4 of relay B, winding Ll, make contact 1 of relay Bto minus auxiliary battery. The application of the auxiliary battery to the line'circuit may produce'a capacitive charging effect on the line circuit of sufiicient intensity to cause amomentary reenergization of relay L, momentarily deenergizing relay R. This, however, has no efiect on the operation of the other relays, except that it may slightly delay the release of the relay T and the energization of X just previously traced. With this switching operation the G2 coil is removed from the circuit; therefore from this point .on the equipment is not aiiected by any differential action of the G relay.

First ground impulse On the first ground impulse from the transmitter the G relay is energized through its winding GI to plus battery and relay L is energized through its winding LE to the minus auxiliary battery. Relay R is released, due to the open circuit through its winding R2 at back contacts of relays L and G. Relay X remains energized despite the opening of makecontact l of relay R from plus through back contact 8 of relay R (this is a'make-berore-break type contact), line 25, make contacts 5 of relay X, line '26, and it of relay B, back contact "S'of relay U and winding X2 to ground. At this time relay Q is energized through the circuit traced from plus through make contact '2 of relay winding'Qi, back contacts l2 of relay Q, "9 of relay R, make contacts 13 of relay B and I of relay L to ground.

T to ground.

as previously described, at the start of the sig- Second break impulse On the subsequent break impulse, relays L and G release due to the opening in the line circuit. This causes reenergization of relay R except that this time both windings RI and R2 are energized through circuits traced as follows: From plus battery through back contact I of relay G, winding RI and make contact 2 of relay Q to ground. Also from plus battery through make contact I4 of relay Q, winding R2, through back contact 2 of relay L to ground. With the operation of relay R, relay U is energized through the circuit traced from plus battery through make contact i of relay TT, line 29, make contact a of relay R, line 30, back contact I of relay Z, make contact I of relay X, winding of relay U and make contact 4 of relay T to ground. Relay U locks in through the circuit traced from plus through make contacts I of relay TT, I of relay U, winding of relay U and contact 4 of relay T to ground.

Code impulses to register On the next (second) ground impulse, relays L, G, operate and R releases as before. In addition the register receives an impulse at this time due to the fact that relay U has. been energized. This circuit may be traced from plus through make contact I of relay TT, line 29, back contact 3 of relay R, line 3I, make contact 2 of relay U, through the register to ground.

On succeeding break and ground impulses relays L, G and R operate as previously covered to record the remainder of the impulses of the code in a similar manner to that just described. The register circuit, however, may be completed through contacts I of relay Y and 2 of relay Z in multiple with contact 2 of relay U for the various digits of the code. The operation of the relays X, Y and Z will be explained at later portion of the description in connection with the automatic selection of headquarters retransmission repeater circuits.

Clearing operations At the end of the code transmission a, long break (minimum of four tooth spaces) takes place before the code springs complete the line circuit at the normal segment. Duringthis break relays L and G release as previously described causing energization of relay R. Relay T releases after a short delay due to the shunt of contact 5 of relay R across its winding T. Relay TT also releases after a delay due to the shunt across its winding by the back contact I I of relay T through line 33, make contact I2 of relay R and line 34, and 2 of relay V (the operation of relay V will be explained later). The position of the slider of the variable resistor I5 may be adjusted for the required drop out time desired on relay TT.

With the release of relay TT the locking circuit for relay Q is broken due to the opening at contact 3 of relay T, 3 of relay TT and 3 of relay Z. (Relays Y and Z release due to openings in the various holding circuits, to be explained in detail later.)

' Second round of signals Let us assume that the transmitter is a multiround type, in which case as the transmitter is in operation, the code springs in passing over the normal segment will cause the following operations: Relays L and G will energize, in turn causing release of. relay R, andoperation ofrelay Q,

nal. Relay TT will reenergize through the circuit traced from plus through back contact I3 of relay R, line 33, back contact it of relay T, winding TT, resistor I5 to ground. Relay T will energize through the circuit traced from plus through make contact 2 of relay TT-the resistor and winding T to ground. This relay locks in through its make contact I of relay T, as before.

On the break impulse after this normal, relays L and G release as before, causing operation of relay R. Relay U is energized through the circuit traced from plus through make contact I of relay TT, line 29, make contact 4 of relay R, line3ll, back contact I of relay Z, make contact I of relay X, winding of relay U and contact 5 of relay T to ground at the same time a shunt is applied across the winding of relay T, by contact 5 of relay R, causing it to drop out after a slight delay. With the release of relay T, relay U drops out due vto the open condition in its circuit at make contact 4 of relay '1.

Clearing operations T energize through circuits previously traced.

Shortly after the operation of relay T, relay TT' drops out due to the shunt across its winding TT by means of make contact I0 of relay T, and back contact II of relay R. Relay B reaches the to openings in its holding circuits at various contacts 5 of relay TT, 5 of relay T and 8 of relay Q. With the release of B, the line circuit is switched so that both ends are connectedto plus battery thereby causing. release of relays L and G. This circuit may be traced as follows: From plus battery, through winding GI, through the line circuit I returning through make contact 6 of relay Q, back contact 8 of relay B, relay winding LI, back contact 3 of relay B, make contact 5 of relay Q, and plus battery. Relay R is reenergized through circuits previously traced through its winding RI and R2, causing energization of relay TT with the subsequent release of relay T which drops out after a short delay. This inturn causes the release of relay TT. Relay Q next releases due to the open condition in its holding circuits through contacts 3 of relay T, 3 of relay TT and 3 of relay Z. This switching operation returns the line circuit to its normal condition and the L relay picks up However, relay B is provided with a retarding winding BF, short-circuited by contact 6 of relay B. This arrangement makes relay B slow operating and prevents its operation on the short impulse .it receives. I

With the operation of relay L, the circuit through the R relay winding R2 is interrupted causing the release of the R relay, which in turn causes the energization of relay 'IT through circuits previously traced. Back contact 9 of relay TT opens and deenergizes winding L2. .Relay 1' also reenergizes with the closing of contact 2 of relay TT. This in turn causes the release of relay TT due to the shunt circuit across'its winding by make contacts H! of relay T and back contact ll of relay R.

Release of relay- R also breaks the circuit for relay X at make contact I of relay R, the other locking circuit through back contact 8 of relay R being open at contacts l6 of'relay B and I! of relay Q. This returns all relays to their normal position and prepares the circuit for receipt of a signal from any other transmitter on the line circuit. Should a second transmitter on the line circuit start operation during these clearing out operations its operation will not be affected. The difference in this case being that some of the switching operations which take place at the start may be omitted depending on the condition of the relays at the time the second transmitter starts.

OPERATION \VITH LEAKAGE ON THE LINE CIRCUIT CASE 1 Leakage on L relay side of transmitter The first case of leakage to be considered will be that of leakage on the line of sufficient value to hold in the L relay preventing it from following subsequent break impulses of the transmitter. On the break impulse following the normal segment when a transmitter is in operation relay L releases and relays B, 'R, and T31 operate as covered in the previous case. However, we assume in this case that after the switching operation has taken place, the leakage will cause operation .of relay L and hold it .in on subsequent signals. Directly following the operationofrelay B, therefore, relay L will reenergize. This is different from the preceding description for normal operation as relay L remained deenergized in that case during the total break impulse. Operation of relay L causes release of relay R due to the open condition in its operating circuit through winding R2 at back contact L. .Relay X now operates; this time through the circuit traced from plus through back contacts 8 of relay R, line 25, E3 of relay Z and $.af relay Y, line 26, through make contact it of relay B, line .27, .backcontact 8 of relay U and winding X2 to ground. On the tion of the auxiliary battery to the line circuit, the operation during the first break impulse is as described above for normal operation; otherwise the operation is for both cases as follows:

On all subsequent coding impulses of the transmitter the relays and register operate as covered under Normal operation except as previously mentioned the L relay does not release at any time. During the long break between rounds of signals and when the code springs are passing over the normal segment, relays G, R, T, TT, Y, Z function the same as covered under Normal operation.

After the last digit of the code of any round of a multi-round transmitter, the relays also function as covered under Normal operation up to the point where the B relay is deenergized. At this point, four conditions may exist as listed below:

1. The L relay may remain energized through the leakage and G deenergized.

'2. The G relay may remain energized and L deenergized.

3. Both relays L and G may remain energized.

4. Both L and G may release as the leakage resistance may be of such a high value that the current will be insufficient to affect either relay. In this case all clearing operations will be as covered under Normal operation.

Condition 1.If the L relay remains energized after the line circuit has been switched by the release of the B relay, the remainder of the clearing operations takes place as follows: With the release of relay G, relay R is energized through the winding RI and make contact 2 of relay Q to ground. Relay TT energizes with the closure of make contact Ill of relay R, through make contacts l3 of relay Q, ill of relay R, H] of relay T and winding of relay TT, through the resistor to ground. Relay T is shunted by make contact 5 of relay R, and drops out after a short delay, in

turn causing the release of rela IT, as previously covered.

In comparing the chart for this condition with that of the normal conditions, it will be noted that no further operation of the relays takes place, as covered under Normal operation. In this case, the Q relay does not release as it is held'in through the circuit traced from plus battery, through winding Q2, make contact 9 of relay Q, and make contact I of relay L to ground.

Condition 2.This case differs from the preceding one in that the G relay energizes and L remains deenergized, due to the leakage efiect. The only difference in operation will be that after the operation of relays R, T and TT, as previously described, relay Q will remain energized, through a locking circuit traced from plus through make contact 2 of relay G, winding Q1 and make contact l l of relay Q to ground.

Condition 3.This case considers the condition wherein the leakage resistance is .low enough to ehold in both the L and G relays, in'which case the difference from the preceding examples will be that relay Q holds in simultaneously through the locking circuits described for the previous two cases. B does not energize in this case and '1 remains operated while TI drops after a delay due to the shunt across its coil through make contact 19 of relay T and back contact I! of relay R,

Condition 4.This case considers the condition where the leakage resistance is so high that neither the L or G relays will hold in at the end of the signal, in which case the clearing operations are as covered under Normal operation.

Cass 2 Leakage effect on G relay side of transm tter Let us assume for this condition that a transmitter is in operation on the lin circuit with the leakage on the side of the transmitter nearest the GI relay winding. On the first break impulse, relay L will release, as'in previous examples, but G may operate through the leakage resistance on the line circuit; if of sufiicient value through the winding GI, as the neutralizing winding G2 is cut off. With the operation of relay'G, a circuit is closed from plus battery, through make contact 2 of relay G, Winding QI, back contacts l 2 of relay Q, 9 of relay R, IA of relay B; lineii'l, 6 of relay TT and make contact 1 of relay T to ground, causing energization of relay Q,which locks itself in through make contact H of relay Q. Thi' will take place before relay B has time to operate as it did in the previous cases, it beingof the slow operating type. When contact '8 of relay Q opens the operating circuit of relay B, its circuit is cut preventing operation at alater time. Relay Q switches the incoming line circuits through make contact 6 of relay W, backcontact 8 of relay B, winding LI, back contact 3 of relay 'B and make contact of relay Q, through resistor to plus battery. It will be noted that for thiscase, the switching of the line circuit has placed bothsides of the line in multiple to plus battery, whereas in the previous case, the two sides of the line were connected between the plus main battery and the minus auxiliary battery; After the energization of relay Q, relay R will energizethrough the cir cuit traced from plus battery, through make contact I 4 of relay Q, winding R2, through back contact 2 of relay L to ground. Operation of R causes TT to energize through make contacts I3 of relay Q, 10 of relay R, line 22, and In of relay T. The remainder ofthe operation will be as coerced under the transmitter operation for the leakage conditions previously described, except that in this case the signal retransmission depends on'the operationcf relay L, relay G holds in on the line leakage; i r i SHUNTED TRANSMITTER.

Should a transmitter that is shunted directly, or is in a shunted loop be in operation, the first break impulseof the transmitter will have no effect on the relays, due to the-shunt. On the first ground impulse, relay windin G2 i shunted out, therefore the G relay is energized bythe current through its winding GI and the-ground at the transmitter. Relay winding Ll also is shunted out by. the same .ground but L may or may not drop out, depending on the speed relationship between it and the operating time of relay G. In any case, however, relay L'will immediately reenergize through the circuit traced from plus through make contact 2 of relay G, line 38, make contact l2 of relay T, line 35, back contacts 26 of relay Q1 and E5 of relay B and winding L2 to ground. Relays Q and [X energize through circuits previously traced for the first leakage case, that is where the leakage affects the L relay except X picks up through contact of relayWQ instead of iii of relay B. Otherwise the remainder of the operation is as covered under Normal op eration, to the point where relays Q, Y. and Z release on the long breakimpulse of the transmitter. In this case, howevendue to the shunt across the box or portion of the line,the line circuit is immediately restored to its normal condition, with the release of Q, thereby causing reenergization of relay L through the normal line supervising circuit previously traced. From this point on the operation of the relays are as covered under Normal operation, from the point where Q releases causing energization of L.

OPERATION WITH LINE CIRCUIT IN TROUBLE CONDITION OPEN CIRCUIT CONDITIONING OPERATION Should a break occur in the line circuit the L relay will release due to the open condition in "the circuit of its winding Ll. This in turn causes operationof relay B through the circuit traced from plus through winding BR, through back contacts f relay Q, Q of relay B and E of relay L to ground. Relay B locks in through the circuit traced from plus battery, through winding BR, back contact 3 of relay Q and make contact 9 of relay B to ground. Simultaneously relay R operates through the circuit traced from plus battery through back contact I of relay G, back contact I? of relay Q, winding R2 and back contact 2 of relay L to ground. RelayTT is energized through make contacts. 5 of relay 3,1!) of relay R, line 22, In of relay T, winding of relay TT and resistor to ground. At the same time a shunt is applied .to relay T by contact. 5 of relay R, which causes .itsrelease after a short delay. With the release of relay T, relay TT drops out, due to the shunt across its winding by back contact H of relay T, line 33, make con-, tact l2 of relay R, line 34, and back contact 3 of relay V. The release of T energizes X through the circuit traced from plus battery through make contact 1 ofrelay R, line 24, back'contacts 4 of relay Y, I of relay Z, 9 of relay T, and wi1 1d ing XI to ground. This completes the relay operations to condition the line circuit for transmitter operation.

TRANSMITTER OPERATION Should a transmitter start operation on either side of the open condition, its ground impulses will control the operation of either the L or G relays. In the case ofthe L relay, the coding impulses will be transmitted from the transmitter ground, through the line, make contact 4 of relay B, winding Ll, make contact 'lof relay B, and resistor to minus auxiliary battery.

On the other side of the open the line coding circuit extends from the transmitter ground through winding Gl to plus main battery.

On the first ground impulse of the transmit ter, either relay L or G operates, causing release of relay R-by breaking the circuit through its winding R2. The remainder of the code operation is the same as covered under Normal operation, except that only one of the line relays will be coding, causing operation of relay R. Re lay Q is not energized. At the time of the long break at the end of the round of signals, either relay L or G will release, causing operation of relay R. This in turn causes release of relays T, TT, Y and Z as previously covered. As the code springs pass over the normal segment, no change takes place in the line relays due to the fact that the line circuit; is open. The remainder oi the rounds ofthe multi round transmitter are transmittedinthe above described manner and the clearing operations will be the same as on the long break at the end of each round.

GROUNDED CIRCUIT OPERATION GROUND CONDITIONING OPERATION Should a line circuit become grounded, that ground will shunt the G2 and LI relay windings, causing operation of relay G, by means of winding GI. The circuit for operation of G may be traced from plus battery through winding GI, through the line circuit to the ground. Relay Q then energizes through the circuit traced from plus battery, through make contact 2 of relay G, winding QI, back contacts I2 of relay Q, 9 of relay R, IQ of relay B, line 31, B of relay TT and make contact I of relay T to ground.

Relay L is temporarily shunted out by the ground on the line circuit but reenergized upon the operation of relay G through its local winding from plus through make contacts 2 of relay G, line. 38, and I2 of relay T, line 35, back contacts I6 of relay Q and I5 of relay B,.and winding L2 to ground. This circuit, is opened, as contact I6 of relay Q opens, but at the same time. the plus battery is applied to the return side of the linethrough make contact 5 of relay Q, back. contact 3 of. relay B, winding LI, back contact 8 of relay B, make contact 6 of relay Q and line. I, i enabling L to remain energized through the ground on the line.

The operation of relay Q causes operation of relay X energizing winding X2 through a circuit traced from plus through break contacts 8 of relay R, line 25, 9 of relay Z, 8 of relay Y, line V 26, contact II of relay Q, line 21, back contact 8- of relay U and winding X2 to ground.

TRANSMITTER. OPERATION On the first break impulse of a code signal, either L or G will release dependingv on which side of the ground the transmitter is operated. This causes energization of relays R and TT and release of relay T in a similar manner to that described for other signals, On the first ground impulse of the first digit of the code, the deenergized line relay L' or G reenergizes, causing release of relay R and energization of relay T. The remainder of the code is transmitted in a similar manner to that previously described.

During the long break. at the completion of the code, relays L or G and R, T, TT, Y and Z function as covered under Normal; operation."

When the line circuit is closed at the normal segment of the code wheel, relay L or G reenergizes, releasing relay R. When the transmitter comes to a stop, this in turn causes energization of relay TT, T and subsequent release of TT, through circuits previously traced for the other cases.

OPEN GROUND TROUBLE CONDITION CIRCUIT CONDITION OPERATIONS Open first-In this case we will consider the condition where the break shortly precedes the ground. On the break in the line circuit, relay L will release, causing operation of relay B, and energization of'relays R, TT, and X in a similar manner to that described for the open circuit trouble condition. Relays T and TT may then release in a like manner, if sufficient time elapses before the ground comes on the line. When this happens, on the return side for this example, the L relay will reenergize through this ground through make contact 4 of relay B, winding LI, make contact I of relay B, resistor to the minus auxiliary battery. This causes release of R due to the break in the circuit of winding R2, at back contact 2 of relay L. Release of R energizes relay TT if it has previously released, through the circuit traced from plus through back contact I3 of relay R, line #3, back contact II of relay T, winding of relay TT and resistor to ground. Closing of contact 2 of relay TT energizes relay T through circuits previously discussed, this in turn causing release of relay TT. Relay X staysv energized from plus through back contact 8 of relay R, line 25, contacts 6 of relay X, line 26, I6 of relay B, line 21, back contact 8 of. relay U, and winding X2 to ground.

TRANSMITTER OPERATION Assuming a transmitter in operation on the grounded side of the line, on the first break impulse relay L releases, in turn energizing R and TT, deenergizing T in a similar. manner to that described for the open circuit trouble condition. On the first ground impulse of the code, relay L will reenergize, causing release of relays R and operation of T in a similar manner to that previously described. The remainder of the code will be-transmitted as covered under Open circuit operation, except when the transmitter arrives at the normal segment at the end of the transmission of the code, relay L reenergizes, throughthe ground trouble on the line circuit, causing release of relay R with subsequent reenergization of relays TT and. T through circuits previouslytraced. Energization of relay T causes release of TT. by reestablishing the'shunt by make contact II] of relay T and back contact I I of relay R across its winding.

Assuming a transmitter to be in operation on the open side of the line, no change will take place on the transmitter operation until the first ground impulse of the code is' transmitted, at which time relay G picks up through its winding GI, this in turn causing energization of relay Q through its winding QI through circuits previously traced. The operation of contact 8 of relay Q breaks the holding circuit for the B relay, causing its release, thereby switching the line relay winding LI from the auxiliary battery to the main battery. On the first break impulse relay G releases, causing energization of relay B. through its winding RI and make contact 2 of relay Q. Relays TT and U energize in succession through circuits previously traced. The remainder of the operation is as covered under ground circuit operation except at the time the transmitter contacts close on the normal segment. As in this case the line is open, the contact closure on the normal segment produces no further effect on the line relay Q, R and X remain energized.

Case 2 .tion of relay G, through its winding GI and the ground on the line circuit to the main battery,

this in turn causing operation of the relays Q I and X. When the open condition occurs, for this case on the outgoing side of the line, relay G will release, causing energization of relay R, through the circuit traced from plus through back contact I of relay G, winding RI, and make contact 2 of relay Q to ground. Relays R and TT function in the same manner as covered in other cases for the first operation of relay R. Assuming a transmitter to be in operation on the grounded side of the line, the first break impulse will cause release of relay L, which in turn causes release of relay Q by breaking its holding circuit through winding Q2 at the make contact L. Relay B will energize through the circuit traced from plus battery through winding BR, through back contact 8 of relay Q, back contact I2 of relay B, and back contact 2 of relay L to ground. B locking in through the operation of its make contacts II of relay B and 9 of relay B. On the first ground impulse, relay L reenergizes, causing release of relay R. The remainder of the operation taking place as covered under Case 1, with a transmitter in operation on the grounded side of theline.

Assuming a transmitter in operation on the open side then the first ground impulse from a transmitter will cause energization of relay G by means of winding GI to plus battery. This in reurn causes release of relay R by the break at hack contact I of relay G. Relays TT and T energize through circuits previously traced. The remainder of the operation will be understood from the above.

GROUNDED OPEN LINE TROUBLE Case 1 In this case we will assume that the open condition occurs before the ground in point of time. At the time of the open condition the relays switch exactly as covered under Open circuit operation up to the point where relay TT releases and X is energized. At this time we will assume that the ground occurs, this will cause energization of relay G through its winding GI to plus main battery. The subsequent functions of the relays R, TT, T and X are the same as for Case 1 under the open ground condition.

Transmitter operation on either side of the line is similar to that covered under Open ground operation.

Case 2 For this ground open condition we will assume that the ground occurs shortly before the open. In this case relays G, Q and X are energized as covered under Grounded operation. On the open the relay operation is the same as for open grounds, Case 2', except that relay L releases inplace of relay G. The operation of the transmitter on either side of this trouble condition is otherwise similar to that covered under Open ground operation.

ROUTING OF SIGNALS In addition to the relays used for line and register control, three relays, namely X; Y and Z are utilized for the purpose of routing the various types of signals. These signals are of the four classes listed below:

1. Special attention 2. Police 3. Fire alarm 4. Routinev Specialattentz'on signals Signals which require special attention by the operator will record on the register with the first digit as a 1. The code wheel of the transmitter, however, will be out with two teeth as has been previously explained; the effect of the first toothof the code is eliminated by the relays.

On the first break or ground impulse, dependingon the line circuit'condition orduring switching arrangements to condition the line circuit for proper operation the X relay is energized as previously covered in the description. As previously explained, relay R energizing on the break impulse following the first ground impulse of the first digit. causes operation of relayU. To review, thisv circuit is, traced from plus through make contact ,I of relay TT, line 29, make contact 4 ofrelay R, line 30, back contact I of relay Z, make contact I of relay X, winding of relay U and make contact 4 of relay T to ground. Relay U locksin through its make contact I of relay U. Up to this time any coding circuit through the register has been open at make contacts I2 of relay U, I of relay Y or 2 of relay Z. On the second ground impulse of the code when relay R releases, a circuit is completed to the register which may be traced from plus battery, through make contact ,I of relay TT, line 29, back contact'3 of relay R, line 3|, make con- I tact 2 of relay U, through the resistor and register coils to ground. At thesame time relay X releases as its holding circuit through winding XI is broken at make contact I of relay R and- Y is energized through the circuit traced from' plus through make contacts! of relayR, line 24, 6 of relay U, back contacts 3 of relay X and 8'of relay Z, winding YI andmake contact 4 of relay TT to ground. Relay Y locks in through itsimake contact 5 of relay Y, at this time.

Due to the longer break impulse at this time (two teeth being removed on the code wheel after the first digit), relay T has time to release due to the shunt efiect of contact 5 of relay R across its winding T. This in turn causes release of relay U due to the opening of contact 4 of relay T in its circuit. At the same time, an impulse is initiated to a special attention relay through the circuit traced from ground through back contact 5 of relay U, makecontact 3 of relay Y and relay 5|]. On the subsequent release of relay R on the next ground impulse, an impulse for the second digit is transmitted through the register of 2 of relay U. At the same time the relay Y locking circuit is established through winding Y2, from plus, through the back contact 8 of relay R,

line 25, make contacts 1 of relay TT, 9 of relay Y and winding Y2 to ground. Relay X cannot be reenergized at this time through winding X2 due to open at contacts 6 of relay X, 8 of relay Y and make contact I of relay U. At this time relay V is energized from plus through back contacts 8 of relay R and 3 of relay U, contact 2 of relay Y and winding VI to ground. Relay V locks in from plus through contacts I of relay TT and I of relay V and winding V2 to ground. This relay operates its contact 2 of relay V thereby introducing resistance into the shunt circuit of relay TT through back contact II of relay T, line 33, and make contact I2 of relay R, reducing its time delay; This is preparatory to the release of TT during, the long break: at'the end of the code. Previously this shunt acted directly across the coil of TT resulting in longer delay, in order. to prevent T from dropping out during the fairly long break after the first digit caused by the removal of two teeth on the code wheel. Without this arrangement a longer break than now used would be necessary at theend of the code where a minimum of four teeth is removed, resulting in reduced code capacity. It is to be noted that only one tooth is removed between succeeding digits, so that the reduced time delay of TT will still be 'sufiicienttokeep it energized' during the longerbreak impulses between the following digits.

On. the subsequent energizat'lon of R, on. the first break impulse of the second digit, no further change takes. place in the routing relays as the circuit of the winding XI is open at contacts '5 of. elay X and back contact 4 of relay Y, and the circuit to winding Zl is open at make Contact 5 of relay X. Relay Y stays locked in through the previous locking circuit traced from plus through make contact I of relay R, line 24, make contact 5 of relay Y, break contact 8 of relay Z, windin Y! and make contact 4 of relay IT to ground. During ground impulses when make contact 1 of relay R is open. and back contact 8 of relay R is closed, relay. Y is held energized from lus through back contact. 8 of. relayR, line 25, contacts l of relay TT and 9; of relay Y and winding Y2. to ground. The. remainder of the digits of the code are transmitted into the register through make contact I of relay Y instead of 2 of relay U and cause no further change in the routing relays. At the completion of the signalrelay Y is deenergized due to the opening of contact 4 of relay to the opening of contact i of relaylTT. An at- V tention relay whose operation will be described at a later point remains locked in. This relay initiates a buzzer and lamp signal to. indicate that the supervis-ors attention is required for the particular signal transmitted.

PoZz'ce signals A signal from a transmitter which requires the attention of the police department will have the first digit or the code record as a 2, the code wheel of course being cut as previously described, with anextra tooth in the first digit. The operation of the routing relays will be. the same as.

covered under Special attention signals up to the point where relay Y is energized. As the next ground impulse occurs after the regular break space, relay T does not have sufiicient time to release before relay R release, relay R sends a second impulse to. the register for the first digit of the code. At the same time relay X is energized through the circuit traced as follows: From plus battery, through back contact 8. of, relay R, line 25, back contact 9 of relay Z, make contact I of short. delaydeenergizing. relay U. 011 the first ground impulse of. the second digit relay V is energized. These operations are the same a explainedin the previous case.

No further change takes place in the condition of the routing relays due to open circuits in the circuits of the various operating windings. The remaining digits of the code are transmitted to the register through circuits previously traced and in addition routed to terminal I3v where they control retransmission to police headquarters re peater relay P. H. Q. This circuit may be traced from ground through back contact 6 of relay R, line 46, back contact. 4- of relay (1, make contact 5 of relay Z, make contacts 8 of relay X and H! of relay Y to the police headquarters. The circuit controls the retransmission over a. headquarters circuit. The ircuit. to the Special attention terminal i2 is also closed as described in themevious case.

Fire alarm signals.

Signals which require the attention of the fire department will record the first digit of 3' 0n the register, which, of course, necessitates cutting the code wheel with four teeth to cover the elimination of the first impulse as previously described. The operation of all routing relays is the same as covered under Police signals up to the time of the second break impulse of the code when the Z' relay is energized. This impulse is of ordinary length, thereby not allowing sufiicient time for relay T to release when during the next ground impulse relay R releases. Relay X deenergizes, as its holding circuit is open at back contact 8 of relay U and back contacts f relay Z or B of relay Y. At this time a third impulse will be transmitted to the register through circuits previously traced. On the following break impulse relay R operates again and relay Y releases, as its holding circuit is open at back contact 8 of relay Z and make contact 4 of relay X. Due to the longer time between digits, relay T has time to release, in turn causing release of relay. U as previously described. On the first ground impulse of the second digit, relay V is energized this time through contact 4 of relay Z instead of. 2 of relay Y.

The remainder of the digits of the code will be transmitted to fire headquarters through the circuit traced as follows: From ground, through back contact 8 of relay R, line 48, back contact 4 of relay U, make contact 5 of relay Z and back contact 9 of relay X to the fire headquarters repeater relay F. H. Q. At the same time a special attention signal is initiated through the circuit traced from ground through back contact 5 of relay U, make contact 6 of relay Z and back contact 2 of relay X to the special attention relay 5%]. Contact 2 of relay Z being closed, permits the remaining digit to be retransmitted to the register.

Night watch. and routine signals These signals have a 4 or higher number as the first digit. In this case. all selector relay operations take place as covered under Fire alarm signals up to the point Where relay Y releases. Due to the fact that the particular break impulse is of normal short duration, it is not sufficient to allow for release of relay T. On the next ground impulse relay X is again energized through the circuit traced from plus through back contact 8 of relay R, line 25, make. contact ll] of relay Z. back contact 6 of relay Y, make contact I of relay U, through winding X2. to ground. On the escapee be thrown, This transfers the trouble light directly to plusjbattery on the main fuse, and silences the buzzer.

subsequent break impulse at the completion of this digit relay X remains energized through winding XI and contact .1 of relay X. For additional ground and impulses for digits higher than 4, no further change takes place withrespect to relays X, Y and Z. On the long break following the first digit, relay T releases causing release of relay U in a manner similar to that previously described. On these signals it will be noted that all circuits are open to the policeand fire headquarters terminals as well'as the special attention terminal. I

TROUBLE INDICATIONS OF OPEN LINE cin- A trouble indication will bra initiated through the circuit traced from ground through back contact I of relay Q, make contact 2 of relay B, in multiple with back contact 2 of relay T, through resistor and. the trouble light through switch blades FS/I and SS/ I in the normal position to the trouble relay. A parallel circuit extends from the above mentioned relay contacts through switch blades 85/2 and FS/Z and the trouble relay. To silence the buzzer associated with this signal, the switch SS shall be thrown, thereby causing release of the trouble relay but leaving the lamp lit by a direct connection to plus battery. Upon restoration of the trouble, the lamp is extinguished due to the open condition at back contact 2 of relay '1 and make contact 2 of relay B. At the same time the buzzer will again sound, this time a circuit being traced from ground through back contacts I of relay Q, I of relay B,

switch blade SS/Z in the right hand position, switch blade FS/Z in the normal position, resistor through the winding of the trouble relay to plus battery. To silence the buzzer the switch SS shall be thrown back to its normal position.

TROUBLE IN DICATION-LINE CIRCUIT GROUNDED The trouble indication for this condition is initiated through the circuit traced from ground through make contact 2 of relay Q, through resistor, the trouble light and switch blades FS/I and SS/I, also through switch blades SS/2 and FS/Z and resistor 15, to the trouble terminal In to operate the trouble relay as previously described. Throwing the switch SS, connects the POWER SUPERVISION Line relay panel fuse In the case where a trouble, particularly in the local circuiting, causes blowing of the panel fuse, all relays release. A circuit is then closed from ground through back contact 2 of relay T, line 4|, resistor, the lamp through switch blades FS/I and SS/ I, also through blades SS/Z and FS/Z and resistor 16, through the trouble relay to plus battery supply, which is not taken through the fuse, it being located on a separate panel unit. To silence the buzzer, the switch FS shall Upon restoration of the powercby replacing the panel fuse "after the -trouble is cleared, the lamp is extinguished and a buzzer signal initiated'through the circuit traced fr m round throu h make contact 6 of relay T,

switch blade FS/2 in the right hand position, resistor, through the troubie relay winding to plus battery. To silence the buzzer the switch FS shall be thrown to its normal position. I

Itwill, be noticed that it is not possible to silence the buzzer signal in any other way but by -,the switch operations indicated; thus giving the operator an indication of the nature of the trouble. 1 V i The preferred embodiment of the various parts ofthe above described system have been shown,

but it should be understoodthat further modifications will occur to those skilled in the art, and therefore it is desired that this invention shall be limited only to the extent required by the prior art and the appended claims.

What is claimed is:

1. In a signaling system, a plurality of code transmitters for transmitting signals of a plurality of types, each transmitter comprising a prefix digit for identifying the type of signal and other digits for identifying the transmitter, first timing means, selecting means responsive to the prefix digit under the control of said first timing means actuated at the end of the prefix digit, second timing means for restoring the selecting means to normal at the end of a signal and means responsive to the first impulse of the second digit for reducing the timing of the second timing means.

2. In a signaling system, a plurality of code transmitters for transmitting signals of a plurality of types, a' plurality of receivers for said types of signals, each transmitter comprising a prefix digit for identifying'the type of signal and other digits for identifying the transmitter, first timing means, selecting means responsive to certain prefix digits for selecting a receiver, said selecting means being under the control of 'said first timing means actuated at the end of the prefix digit, second timing means for restoring the selecting means to normal at the end of a signal and means responsive to the first impulse of the second digit for reducing the timing of the second timing means.

3. In a signaling system, a code transmitter fortransmitting signals comprising a prefix digit for identifying the signal and other digits for identifying the transmitter, a plurality of receivers, routing means responsive to the prefix digit for switching the signals to the proper receiver, timing means for restoring the routing means to normal at the end of a signal, another timing means responsive to the end of the prefix digit for switching the remainder of the code, switching means responsive to the first impulse of a second digit for reducing the timing of the first timing means and contacts operated by the routing means for operating the switching means.

4. In a signaling system, a code transmitter for transmitting signals comprising a prefix digit for identifying the signal and other digits for identifying the transmitter, a repeating relay for repeating the code signal, a plurality of receivers, routing means responsive to the prefix digit for switching the signals to the proper receiver, timing means for restoring the routing means to 1- 5.111 -a signaling system, a code transmitter for-transmitting signalscomprising a prefix digit ioridentifying the signal' followed by a plurality of digits identifying the transmitter, a plurality prefix digit for routing'the -signals to theproper receiver, -a timing relay responsive to the end-of a signal for restoring the-routing means to nor -mal-,-another timing relay-responsiveto the break 'lO of receivers -routing ineans'responsive to the V afterthe prefix digit for timing'the prefix,'-a

switching relay responsive tothe first impulse of the seconddigit for reducing the timing- 0f the first timing relay and "contacts operated by l the routing Tfor iopemti hing 'relayn'. j i h v -"6.'In a signalingsystem 1a coda-transmitter fortransmitting. signalsicomprising:aiprfixodigit -for identifying thesignal'followed'by aaplurality of digits identifying the transmitter a repeating relay for repeating the digits, .a 1P1l1IaIltyiDfiT-e ceivers, routingimeans :responsive to thenpre'flx digit for routing the signals tot-the proper rebeiver,

a timing relay:responsive -toslthe en'dcofeaizsignal *for restoring the routing means to normalgam other timing relay responsive to thebreak: after the-prefix digit-for timing the prefix, a switching relay responsive to the f r'st impulse of the second digit for reducing the timing of the first timing 1 elay andcontacts'operated bythe rou'ting means "for" operating the switching relay.

FMANFREDIW. MUEHTER. 

